In the past, as an exhaust gas purification catalyst arranged in an exhaust passage of an internal combustion engine, there has been developed an electric heating catalyst (hereinafter referred to as an EHC) in which a catalyst is heated by means of a heat generation element which generates heat by electrical energization thereof.
In the EHC, an insulating support member, which serves to support the heat generation element and to insulate electricity, is arranged between the heat generation element which generates heat by electrical energization thereof, and a case in which the heat generation element is received. For example, in Patent Document 1, there is disclosed a technique in which in an EHC, a mat of an insulating material is arranged between a carrier which is electrically energized to generate heat and a case in which the carrier is received.
In addition, in Patent Document 2, there has been disclosed a technique related to a condensation device which causes exhaust gas fine particles to be charged and condensed by generating a corona discharge in an exhaust pipe of an internal combustion engine. The condensation device in Patent Document 2 has an electric conductive part that serves to conduct a high voltage to an electric discharge part, and an insulator part that serves to hold an outer periphery of the electric conductive part. A ring-shaped protrusion portion is formed to protrude from an outer peripheral surface of the insulator part in a diametrical direction thereof, and an oxidation catalyst layer is formed in the protrusion portion.
In Patent Document 3, there is described that in a filter substrate of a catalyst for purification of diesel exhaust gas, an inflow side oxidation catalyst coat layer, which includes at least one kind of substance selected from alkali metals and alkaline earth metals, is formed on a cell partition surface at the side of an inflow side cell, and an outflow side oxidation catalyst coat layer, which does not include an alkali metal and an alkaline earth metal, is formed on a cell partition surface at the side of an outflow side cell.